It happened at the Weston Club apartments, a retirement community on Hailey Drive.

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March 11, 2013: The couple's son found them when he visited their home at the Weston Club apartments, a senior living community on Hailey Drive.

Updated at 12:24 PM EST on Tuesday, Mar 12, 2013

An elderly couple was found dead inside an apartment in Marlton, NJ.

Investigators say that the couple's son found them unconscious when he visited their home at the Weston Club apartments, a senior living community on Hailey Drive. They were pronounced dead after officers and medical crews arrived at the scene.

A Fire Department spokesman told NBC10's Cydney Long that there is sufficient evidence to suggest that it was a double suicide and that they may have inhaled some sort of substance.

Experts on aging say that couple make the decision to kill themselves for reasons like guilt over being a burden or as an act of devotion.

Dr. Stephen Treat, CEO and Senior Staff Therapist for the Council for Relationships, says that often times senior couples decide to commit suicide together because they can't live without the other person -- it's just too painful for them.

"Some couples become so co-dependent on each other, that they can't see a future where they can live without their partner," Dr. Treat said. "...There is so much illness, pain or exhaustion that they just say 'enough' and choose to end it."

Investigators are awaiting autopsy results to determine an exact cause of death.

Crews tested for carbon monoxide, but none was detected and the building was not evacuated.